According to known construction, a masonary saw consists of a saw blade rotating about a horizontal axis with a reservoir pan being located beneath the saw blade for retaining a coolant which is continuously pumped from the pan onto the saw blade while the saw blade is in use. A sliding platform mounted on tracks directly within the reservoir is provided for moving a workpiece beneath the circular saw blade. Such a construction is shown in U.S. Pat. No. 3,635,206 issued Jan. 18, 1972 to Harclerode.
Unlike conventional saws, the sliding tray of a masonary saw cannot be permitted to have any angle adjustment relative to the saw blade. This is required because the mounting tracks on which the platform slides are, as described above, located directly in the coolant reservoir which would spill its contents if it were tipped out of the horizontal plane. Therefore, because the platform is not adjustable, a separate mitre guide attachment must be provided on the platform in order to produce mitred cuts in a work piece cut by the saw blade.
Very few efficient safety oriented jigs have been developed for use with a masonary saw as described above, for producing the required mitre cuts. As will be appreciated, masonary saws are very dangerous to work with and there is a great need to develop a safety conscious mitre guide jig that is adapted for use with a masonary saw. The prior art structures include arrangements such as that described in U.S. Pat. No. 3,463,137 issued Aug. 27, 1969 to M. J. Hare showing a jig which is used to hold a work piece principally a brick, at an angle relative to a saw blade for producing a mitre cut in the brick. However the reference structure is not readily useable as an attachment to a sliding platform, but rather includes its own sliding arrangement, in lieu of the platform. This of course, increases costs substantially. Furthermore, the reference structure presents a severe safety hazard because it does not include any support means for supporting the work piece in the direction of travel of the saw blade relative to the work piece. Therefore, the operator must place his or her hands, in the cutting area to prevent shifting of the work piece along the jig. This, of course, can result in severe injury, should the operator not be extremely careful. Any one who has worked with these dangerous circular saws, will appreciate that even the slightest lack of concentration can result in the loss of a finger or a hand.
A further drawback of the reference structure is that it does not include any type of adjustable height support for raising or lowering of the work piece relative to the saw blade. Therefore, it is limited to use only with work pieces of a certain fixed height thereby, substantially reducing the versatility of the structure.
A further important feature in a mitre guide is that it should permit cutting of the work piece from both the right hand side and the left hand side of the saw. Although the jig of U.S. Pat. No. 3,463,137 does include this feature, it requires two separate and distinct supporting surfaces for the right and the left hand cutting of the work piece. This again, makes the reference structure quite complicated and expensive to construct.
The present invention provides an uncomplicated, easy and safe to use, jig for a masonary saw which comprises a body portion having a single work piece receiving flat face and an end portion to which the body portion is adjustably secured to vary the position of the work piece receiving face. The end portion is provided with clamping means to clamp the jig to a masonary saw platform, thereby making the jig readily useable with a masonary saw.
The body portion is adjustable to vary the position of the work piece receiving face from an extreme left hand cutting position to an extreme right hand cutting position such that only the single face is required for cutting from either the right or the left hand side of the saw.
For purposes of safety, the body portion is provided with at least one upstanding end rail bordering the end of the work piece receiving face to prevent sliding of the workpiece on the face while cutting. This eliminates the need for the operator to hold the work piece in the cutting area while it is being cut by the saw blade.
The jig is provided with a support bar which is adjustable in position relative to the work piece receiving face and extends across the face at essentially right angles to the end rail, and means for locating the support bar at a plurality of different supporting positions on the tile receiving face. According to a preferred and simple construction, the body portion is notched at intervals to receive the support bar at the different positions. Other mechanical means can also be used to move the bar to different positions so that the support bar provides a height adjustment on the work piece receiving face to expose the desired amount of work piece to the saw blade.